Give reason for the following
In angiosperms, one of the male gametes fuses with egg to form zygote and second male gamete fuses with polar nuclei to form primary endosperm nucleus.

How many male gametes are formed in pollen tube of angiosperms?

Mention the reason for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm?

Choose the correct answer : Male gametes in angiosperms are formed by the division of :

Long Answer Questions Five mark Each QUESTIONS FROM CBSE BOARD EXAMINATIONS : Give reasons why : (i) most zygotes in angiosperms divide only after certain amount of endosperm is formed. (ii) groundnut seeds are exalbuminous and castor seeds are albuminous. (iii) micropyle remains as a small pore in the seed coat of a seed. (iv) integuments of an ovule harden and the water content is highly reduced as the seed matures. (v) apple and cashew are not called true fruits.

ADDITIONAL QUESTIONS : The diagram below shows a germinating pollen grain and a mature ovule from an insect-pollinated flower. Some parts have been labelled. Give the letter of the nucleus which fuses with a male nucleus to form each of the following : (i) The zygote (ii) The endosperm

With the reference to the following figure of stages of a microspore maturing into a pollen grain, answer the question. How many mitotic divison takeplace to form two male gametes ?

Which of the following situations correctly describe the similarity between an angiosperms egg and a human egg? Eggs of both are formed only once in a lifetime Both the angiosperm egg and human egg are stationary both the angiosperm egg and human egg are motile transported Synagamy in both results in the formation of zygote Choose the correct answer from the options

Given below are a few statements related to external fertilization. Choose the correct statements. The male and female gametes are formed and released simultaneously Only a few gametes are released into the medium. Water is the medium in a majority of organisms exhibiting external fertilization. Offspring formed as a result of external fertilization have better chance of survived than those formed inside an organism.

In these question, a statement of asertion followed by a statement of reason is given .Choose the correct answer out of the following choices: Assertion and reason both are correct statements and reason is correct explanation for assertion. Assertion and reason both are correct statements but reason is not correct explanation for assertion. Assertion is correct statement but reason is wrong statement. Assertion is wrong statement but reason is correct statement. Assertion:In a movie,ordinarly 24 frames are projected per second from one end to the other of the complete film. Reason:The image formed on retina of eye is sutained upto 1//10 s after the removal of srtimulus.